Nowadays, a lighting apparatus using a light-emitting diode (LED) which is a semiconductor light-emitting element is widely proposed as a substitute for a conventional lighting apparatus for the purpose of energy conservation and for other various purposes. In addition, the LED holds promise also as a light source for color tone-variable illumination which has been difficult to realize with a conventional light source. As one example of the lighting apparatus, there has been disclosed a lighting apparatus in which a red LED, a green LED and a blue LED are built into a single package to output white light (see, for example, Patent Document 1). In this technology, contrivances are made to adjust drive currents supplied to the abovementioned three types of LEDs according to the forward voltage of each LED, in order to keep the luminous efficiency of each LED constant and stabilize the luminance of white light, as well as to emit light having various hues.
In addition, as lighting techniques utilizing LEDs, there have been disclosed techniques to combine semiconductor light-emitting devices for emitting red, blue and green light using a blue LED and phosphors for red and green color development and control the output of the LED, thereby tracing a black body radiation locus and emitting white light close to natural light (see, for example, Patent Documents 1 to 3).
Yet additionally, there have been proposed a color-tunable (color tone-variable) semiconductor light-emitting device, a light-emitting module, and the like, configured to emit light to the outside by means of light emission from a package in which semiconductor light-emitting elements are mounted, wherein the output plane of light from the package is divided into a plurality of regions, and semiconductor light-emitting elements and fluorescent portions are disposed in the respective regions in correspondence with each other, so that the spectrums of light output from the output plane differ from each other (see, for example, Patent document 4). In this type of semiconductor light-emitting device or the like, power to be supplied to a corresponding semiconductor light-emitting element is controlled for each region of the output plane of the package divided into a plurality of regions, for example, so as to be able to adjust the color temperature of light output from the semiconductor light-emitting device.                Patent Document 1: Japanese Patent Laid-Open No. 2005        Patent Document 2: Japanese Patent Laid-Open No. 2007-265818        Patent document 3: Japanese Patent Laid-Open No. 2007-299590        Patent document 4: Japanese Patent Laid-Open No. 2009-231525        